Caribbean disturbance 94L dumping heavy rains on Jamaica

By: Dr. Jeff Masters , 4:44 PM GMT on June 05, 2011

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A large, wet, and disorganized tropical disturbance (Invest 94L) continues to spread heavy rain to the Central Caribbean near Jamaica. Rain has fallen continuously at Jamaica's Kingston Norman Manley Airport since midnight, with 1.89" having fallen from midnight to noon local time. Sustained winds of 24 mph also affected Kingston between 7am and 8am this morning. Satellite-estimated rainfall amounts of 1.4" per hour occurred in ocean regions 100 miles to the southeast of Kingston this morning, and heavy rains of up to 1/2" per hour are probably affecting portions of Jamaica early this afternoon, judging by the recent increase in heavy thunderstorm activity seen on visible satellite loops. This imagery also shows a slow increase in organization of 94L in recent hours, with spiral bands beginning to develop to the southeast of the center. There is a broad, poorly-defined circulation apparent that is not well enough defined to make 94L a tropical depression. Water vapor satellite loops show a region of dry air on the west side of 94L, and this dry air is interfering with the storm's organization. However, upper air balloon soundings from Kingston and the Cayman Islands taken at 8am EDT this morning show much moister air at mid levels of the atmosphere compared to Saturday (2% humidity at 500 mb on Saturday, compared to 49% this morning at Grand Cayman), and 94L appears to be gradually overcoming its dry air issues. Wind shear remains in the moderate range, 15 - 20 knots, and is predicted by the SHIPS model to remain below 20 knots through Tuesday morning. Water temperatures in the Central Caribbean are about 1°C above average, 28 - 28.5°C, which is 2°C above the threshold needed to support development of a tropical storm.


Figure 1. Rainfall rates of up to 1.4" per hour (pink colors) were estimated by the F-15 satellite for 94L at 6:02am EDT Jun 5, 2011.

Since 94L is so large and is battling dry air, it is taking its sweet time to develop, and today's mission by the Hurricane Hunters has been cancelled. A new mission is scheduled for Monday afternoon at 2pm EDT. This morning's 06Z model runs are pretty unimpressed with 94L, with most of them showing little or no development. At 2pm EDT on Sunday, NHC gave the disturbance a 40% of developing into a tropical depression by Tuesday. If 94L stays to the south, its chances of development are greater, since a band of very high wind shear of 30 - 50 knots lies over Cuba and the southern Bahama Islands. The disturbance is expected to meander slowly westward or northward over the next two days, with Jamaica and southeastern Cuba being the primary targets for very heavy rains of 4 - 8 inches through Tuesday. Haiti and Central Cuba can expect somewhat lesser rains of 3 - 6 inches. If 94L does develop into a tropical depression and moves northwards over Cuba by Wednesday, I don't see the storm attaining hurricane strength, due to the high wind shear. The primary threat from 94L will be very heavy rains, capable of causing life-threatening flash flooding.


Figure 2. Afternoon satellite image of the Central Caribbean disturbance 94L.

Jeff Masters

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its 1007.6 and falling
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Quoting kmanislander:
Taking a break now. Back later



ok have a good break
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Quoting xcool:
50%
Is that from the outlook or from your guess?.
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493. xcool
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Taking a break now. Back later
Member Since: August 19, 2006 Posts: 0 Comments: 15798
Quoting PcolaDan:


You shouldn't have a problem with that. I mean c'mon, you interviewed these guys didn't you?

EAST -

WEST -



During active periods of hurricane season, these rules will be strictly enforced. Violations will be met with a minimum 24 hour ban.


with 94L geting its act togeter we are now in a active period wish means some ruls may be strictly enforced so i would watch what you post and keep evere thing re rated too 94L so in other words what you are posting is not re rated too 94L
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Question for those whom have been here awhile .. which model seems to be more accurate?
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489. xcool
94l move to nw hmmm
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114. Sammy

OK, I see ur point. Track needs to at the most edge the western side. Thing is, as lopsided as this is, and is likely to continue to be, a much more easterly track would also lead to limited precipitation....
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486. xcool
50%
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Quoting kmanislander:
Levi

New surface pressure map places the area of lowest pressure just West of that convective blow up


Yeah, thats what I was saying earlier. Looked pretty conclusive on visible satellite.
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Quoting kmanislander:
Levi

New surface pressure map places the area of lowest pressure just West of that convective blow up



I agree with that position.
Member Since: November 24, 2005 Posts: 635 Comments: 26586
94L has become really healthy since yesterday, convection now on the western end of the (new?) COC.
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94L Multiplatform Satellite Surface Wind Analysis

Member Since: July 3, 2005 Posts: 423 Comments: 127804
Also note the thunderstorms going off on the far west side of the circulation just north of Honduras. The atmosphere is slowly moistening up in the NW Caribbean, making the way a bit easier for 94L as it drifts in that direction.
Member Since: November 24, 2005 Posts: 635 Comments: 26586
Levi

New surface pressure map places the area of lowest pressure just West of that convective blow up with the cloud deck entering the Eastern half of the center position.

Member Since: August 19, 2006 Posts: 0 Comments: 15798
Quoting sammywammybamy:


^ Ok.

Without Futher Adu:

Due to the Unusual Lack of a Poll Question , I Must Compensate for this Error

POLL:

What is the Percantage on the Next Two for 94L

A) 30%
B) 40%
C) 50%
D) 60%
E) 70%
F) Shower Curtains!
C or D
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Quoting alfabob:
Yep that larger mid-low level rotation to the south of Jamaica should be absorbing the surface low. It has much stronger inflow and you can already see it starting to merge in the SW quadrant.


Yep, and on rainbow notice the convection beginning to wrap around the mid-low level COC.
Link
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Quoting sammywammybamy:


^ Ok.

Without Futher Adu:

Due to the Unusual Lack of a Poll Question , I Must Compensate for this Error

POLL:

What is the Percantage on the Next Two for 94L

A) 30%
B) 40%
C) 50%
D) 60%
E) 70%
F) Shower Curtains!


I think it's a little early for this poll lol, the TWO is still three hours out, a lot could change by then, or we could at least know more. At the minute, my guess would be B.
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474. ackee
Quoting Tazmanian:





i pick F
B
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Fleet Weather Center Norfolk Tropical Feed
No Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
By Maritime.CDO@navy.mil (FWC-N CDO) from Fleet Weather Center Norfolk Virginia. Published on Sun, Jun 05, 2011.

As of Sun, 05 Jun 2011 20:00:01 GMT

2011 Storms
All Active Year


Atlantic
94L.INVEST

East Pacific
91E.INVEST (T.C.F.A.)

Central Pacific

West Pacific
92W.INVEST

Indian Ocean
98A.INVEST

Southern Hemisphere
Member Since: July 15, 2006 Posts: 170 Comments: 53497
Quoting sammywammybamy:


^ Ok.

Without Futher Adu:

Due to the Unusual Lack of a Poll Question , I Must Compensate for this Error

POLL:

What is the Percantage on the Next Two for 94L

A) 30%
B) 40%
C) 50%
D) 60%
E) 70%
F) Shower Curtains!





i pick F
Member Since: Posts: Comments:
Quoting sammywammybamy:


^ Ok.

Without Futher Adu:

Due to the Unusual Lack of a Poll Question , I Must Compensate for this Error

POLL:

What is the Percantage on the Next Two for 94L

A) 30%
B) 40%
C) 50%
D) 60%
E) 70%
F) Shower Curtains!

C or D
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Quoting stormwatcherCI:



Pressure in East End down to 1006 mb and winds are East @ 25 mph.


1008.4 here and falling
Member Since: August 19, 2006 Posts: 0 Comments: 15798
Quoting Levi32:
I still contend that the low center is west of the convection. SW inflow directly into a thunderstorm complex does not imply a low center there, as air flows around a low center, not directly toward it, courtesy of the coriolis force. If you turn on lat/lon lines, the center of rotation appears to be near 79.5W at the end of the loop.


I agree with that fix, looks like circulation is centred there. Interesting to note that on the last few frames there is convection firing up near that centre.
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Quoting sammywammybamy:


My Bad...

Grothar confused me...

He made an accidental typo... its okay Grothar!


I Always though that the worst quadrant of a tropical cyclone is the North East Quad...


Sorry, sammy, If you think you're confused, you should see me at medicine time. Even though most storms normally have the strongest weather to the North and East, Hurrican Katrina, when it hit Ft. Lauderdale and Miami, actually had the worst weather to the South and West for most of the storm.


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94L Enhanced Infrared (IR) Imagery (4 km Mercator) Loop
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting kmanislander:


Could be. Either way the center is on the way to being covered over. There is less than a degree separating us in terms of center position.


It's true. I guess I just love visible satellite interpretation.
Member Since: November 24, 2005 Posts: 635 Comments: 26586
if this goes over cuba, wont the center relocate..it did it with ernesto and ended up hitting south florida head on and didnt even go into the GOM..
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We have another lower diurnal cycle at the buoy just west of 94L, indicating that the system may finally be seeing a slow deepening trend that has been absent thus far in its life cycle. It will be interesting to see how low the pressure gets later tonight during the next diurnal period once the center of 94L is closer to the buoy.

Member Since: November 24, 2005 Posts: 635 Comments: 26586
Looking at the Vorticity maps that Kman was showing added with visible imagery i will go out on a limb and say that a Tropical Depression is most likely forming right now or will form tonight...it is extremely close...though i do think we will not have confirmation of this until tomorrow
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Quoting Levi32:
I still contend that the low center is west of the convection. SW inflow directly into a thunderstorm complex does not imply a low center there, as air flows around a low center, not directly toward it, courtesy of the coriolis force. If you turn on lat/lon lines, the center of rotation appears to be near 79.5W at the end of the loop.


Could be. Either way the center is on the way to being covered over. There is less than a degree separating us in terms of center position.
Member Since: August 19, 2006 Posts: 0 Comments: 15798



Pressure in East End down to 1006 mb and winds are East @ 25 mph.
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Quoting washingtonian115:
But 94L doesn't even have a name and it's effecting people in a great way(Flooding problems in the carribean)


I completely agree, I think it's easy to only be watching possible tropical storm formation and to forget about the problems that this system is causing already.
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I think we will see a TD earlier than some people think..just from my personal forecasting experiences when a storm takes a long time to conslidate once it gets going it can take off quick...Tropical Storm Alex of last year comes to mind with a quick developing near the Yuctuan
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I still contend that the low center is west of the convection. SW inflow directly into a thunderstorm complex does not imply a low center there, as air flows around a low center, not directly toward it, courtesy of the coriolis force. If you turn on lat/lon lines, the center of rotation appears to be near 79.5W at the end of the loop.
Member Since: November 24, 2005 Posts: 635 Comments: 26586
it seems on vis loop that the LLC is getting dragged back and into the MLC you can see the LLC becoming elongated W-E
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Quoting NICycloneChaser:
Looks like the EPAC is just going to beat the Atlantic to the first storm of the season. NOAA predicts 15 in both basins, so we have something of a competition on the cards.... Haha


NOAA is predicting 9-15 in the EPAC basin, or an average of 12. So slightly less for EPAC.
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Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting sammywammybamy:


See Post 420 for Directions
:) I know how to do it but I was trying to tell her in the easiest way since she already had the properties.
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GFDL Along-Shear Vertical Cross Section - Wind Speed & Relative Humidity

Member Since: July 3, 2005 Posts: 423 Comments: 127804
449. IKE

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Quoting NICycloneChaser:
Looks like the EPAC is just going to beat the Atlantic to the first storm of the season. NOAA predicts 15 in both basins, so we have something of a competition on the cards.... Haha
But 94L doesn't even have a name and it's effecting people in a great way(Flooding problems in the carribean)
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Quoting ackee:
DO u guys think 94L centre has relocated ?

not yet
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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